If we talk about hibernation, during this process, all vital signs are practically reduced to zero. The body temperature of the animal drops and becomes only slightly higher than the air surrounding it. This is what reduces energy consumption. If external factors environment change, for example, if the temperature in the den drops, then the animal wakes up, warms up (burrowing into the snow or bedding) and falls asleep again. Thanks to this, it is possible to save more heat, therefore, there will be less energy consumption, and the bear will safely endure in order to get out into the forest again in the summer.

Features of hibernation

It is known that not all bears hibernate. Polar are different from their European relatives. While the rest are quietly sleeping in their dens, they are actively looking for food. An exception to the rule are pregnant females, who hibernate for several months until they have babies. After the birth of the cubs, the bear leaves the den and continues active life in search of food.

It is better to never wake up a bear sleeping in a den, as a clubfoot wakes up at one moment, while it becomes 100 times more dangerous. Such cases are extremely rare for a person to stumble upon a lair in winter. Bears choose very secluded places in the forest, where, perhaps, a human foot has not even set foot.

Scientists have been trying to unravel the mystery of the forest giant for more than a year. After all, it has not yet been definitely identified, which allows them to be in complete hibernation for up to 7 months. By answering this question, scientists hope to make substances used by animals and for humans. This, in turn, will help a person safely fall into a long sleep without harm to the body. One way or another, all this is just a development, but for now people are left to envy the heroic dream of a bear.

The closest relative of the brown bear. They descended from common ancestors who lived only 150 thousand years ago (for the evolution of species, this is quite recent). The brown bear perfectly hibernates in the winter, and can the polar bear sleep in the den in the summer?

And in general, if the dens polar bear?

Surprisingly, almost no sleep! That is, they sleep normally, just like in summer (only in summer they usually sleep more). But in winter dream they don't fall. (“Hibernation” of bears is more correctly called winter sleep; bears do not have real hibernation, since their body temperature almost does not drop, and at any moment they can wake up.) Only pregnant and nursing females fall into winter sleep. The rest of the polar bears, if they lie in dens, then not for long and not every year.

The main food of polar bears is seals. These are such seals. They are hunted by polar bears on the ice. They either snatch the seal with their paw from the hole in the ice through which the seal breathes, or lie in wait and grab the seals that have climbed out onto the ice to rest. In many areas of the Arctic where polar bears live, the ice almost completely melts by the end of summer. They can no longer hunt seals. On land, most arctic animals are able to run away from a polar bear, and in the sea they can swim away from it. It is good if you manage to find the carcass of a dead whale or walrus on the shore. And if not, then at the end of summer and autumn, bears sometimes go hungry for several months. So in winter they do not sleep, but start hunting again as soon as the ice appears.

But the females have nowhere to go - they have to lie in dens. After all, polar bear cubs, like other bears, are born small (their mass is less than a kilogram) and blind; they are covered only with short down. Usually females arrange a lair on the shore, sometimes 50 km from the seashore. As a rule, a she-bear makes a lair in a snow dune, but if there is little snow, she can also dig a hole in frozen ground. The female lies in the den just when the ice melts and it becomes difficult to hunt. Bear cubs are usually born in November-January, and remain in the den until February-March. Before the birth of the cubs, the mother bear really mostly sleeps, but during childbirth she wakes up, and after childbirth she has to sleep less. However, she is still in a state of winter sleep before leaving the den: she does not eat, drink, pee or poop.

How does the female manage to accumulate nutrients for a long sleep and for feeding cubs (and there are usually two of them)? It turns out that polar bears mate in the spring - in April-May. Immediately after mating, pregnant females begin to eat so intensely that by autumn they become 200 kg heavier - their weight sometimes almost doubles! At the same time, the development of embryos in the abdomen of a bear in the spring stops at early stage and continues only in autumn; before that, they are at rest (scientifically called embryonic diapause). Apparently, this allows female bears to "adjust" the beginning of embryo development to the time of entry into the den; after all, this time depends greatly on the conditions in a given area and even on the weather in a given year.

It is not very clear why all the polar bears should not eat too much. But for some reason they don't.


It is interesting that, apparently, at any time of the year, during prolonged starvation, polar bears seem to “sleep on the go.” In their blood, the concentration of urea drops sharply, which is typical for other types of bears during hibernation. Bears are able to use urea for the synthesis of amino acids and proteins of the plasma (liquid part) of the blood. (Plasma protein concentrations should be kept as constant as possible, otherwise there are various problems with fluid transport and metabolism in the body.) In addition, the lower the urea content, the less it needs to be excreted in the urine, which means less need to drink. Although water in the form of snow is usually readily available in the Arctic, drinking (or rather, eating) it is energetically unprofitable - a lot of energy is wasted on warming it.

If a brown bear's urea concentration has dropped, it becomes lethargic, no longer wants to eat, and falls asleep. But the polar bear, in the presence of food, begins to eat again and raises the concentration of urea to a normal level.

Interestingly, during the period of winter sleep, the polar bear somehow manages to almost not lose bone and muscle mass. Usually, in humans and other animals, their mass decreases sharply with prolonged immobility, even when there is food; the mass of bones and muscles also decreases in other species of bears during sleep. But the polar bear consumes almost only fat. It turns out that in some respects, polar bears are more adapted to winter sleep.

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Nature uses many mechanisms to protect plants and animals from harmful effects. external factors and dangers. speed, strength, sharp teeth, poison - all these are active means of survival. Camouflage, symbiosis and suspended animation are passive methods that help you survive. The article will tell about the hibernation of bears, answer questions about how bears prepare for winter, when bears go to sleep when they wake up.

What is hibernation

Hibernation is a time of slowing down of life processes and chemical metabolism in the body of warm-blooded animals. The main characteristics of this condition are: a decrease in body temperature by several degrees, breathing becomes rare, slowing of the heartbeat, and inhibition of physiological processes. Hibernation is used by animals for self-preservation during periods when it is difficult to find food, when extreme cold sets in. The condition can last from a few days to many months.

What animals can hibernate

Since childhood, everyone knows that in winter it hibernates, during which it sucks its paw, and wakes up only in spring. And the answer to the question of when bears hibernate is known even to children - in late autumn.

In fact, bears do not go into true hibernation, which is essentially a suspended animation of the body. They only fall into a light sleep, waking up easily when disturbed. During this sleep, the body temperature of the bears drops to 31 ° C, while normal temperature the beast is approximately 38 °C. For comparison: the body temperature of the American ground squirrel, which in active state equal to 38 °C, during hibernation drops to zero! Still, Toptygin's body works in economy mode, the number of heartbeats decreases to ten per minute, metabolic processes slow down several times.

How a clumsy bear prepares for hibernation. Fat accumulation

In order to successfully overwinter, you need to solve two questions:

  • accumulate energy reserves;
  • prepare a room for wintering - a lair.

Energy reserves are fat. To accumulate it, the bear spends the whole summer in active search food. He loves sweet forest berries, especially raspberries and strawberries, but he is picky in food and eats roots, ants, fish, small mammals. The underskin layer of fat in bears closer to cold weather reaches a thickness of 7-9 cm. Females gain weight up to 150 kg or more, males - up to 300 kg, with 1/3 of the total mass falling on fat.

A few days before leaving for the winter, they stop eating and actively empty their intestines. After all, when bears go into hibernation, they do not eat for six months, do not drink water and do not defecate.

Preparing the lair for wintering

The second thing is to prepare a shelter - warm enough to shelter from the frost, and safe enough not to become easy prey for the enemy.

The bear chooses a place for a future den very carefully. Depending on the species, this may be a depression between tree roots, a cave or a rocky niche, an abandoned anthill, a tree hollow. Sometimes bears dig dugouts, strengthening the walls with boughs, very rarely they build riding dens - a structure made of branches on the ground, resembling a large bird's nest.

The bottom of the rooming house is covered with spruce branches, peat, moss, dry leaves, hay, and when bears go to sleep, they are warm and comfortable in their bed.

The dimensions of the den are not much larger than the body of the animal. Toptygin always leaves a hole through which air enters his shelter. Surprisingly, the snow, completely falling asleep in the den, never falls asleep in the "window", so successfully the bear knows how to choose a place for it.

What month does a bear hibernate?

Scientists have long been studying this natural phenomenon like hibernation. Much attention is paid to physiological processes such as metabolism and changes in metabolic reactions. Scientists are also interested in when bears hibernate. In Siberia and in Europe it happens in different time. The following factors matter:

  • gender, age and physiological state of the animal;
  • yield of bear feed;
  • natural area;
  • weather.

Pregnant females and mothers with cubs are the first to leave for the winter in early November. Barren she-bears and males at the end of November, and in southern regions may last until mid-December.

In years with a particularly large harvest of nuts, acorns, these dates are shifted by a few more weeks closer to winter.

If for some reason the bear did not have time to work up fat for the winter or arrange a dwelling for himself, then he does not hibernate. Such animals are called rods. They are very dangerous because they behave aggressively and viciously.

Now the reader knows what time the bear goes to sleep and how he prepares for it. It remains to be clarified that Toptygin leaves the lair in the south already at the end of February, in the middle latitudes - in March, in the north - in April. Thus, wintering can last from 2.5 to 6 months.

Up to 3 meters tall, up to 1000 kilograms of weight - bears can have such parameters, depending on the subspecies. A powerful body, a massive head, claws - hardly anyone dreams of meeting such a one-on-one, so it’s worth going into the forest where this representative of predators is unlikely to be found.

The second option is to go there in winter, when the bears hibernate. But at the same time, you need to remember that not all bears go to the den in cold weather. Those representatives of formidable predators that live in more warm countries, are quite capable of existing without seasonal sleep. Although the same polar bears, which do not live in hot latitudes, also do not hibernate. The exception is their lactating or brooding females. Everything has an explanation.

What is bear hibernation?

From a scientific point of view, the hibernation of a bear is not a complete sleep. When an animal lies in a den, its metabolic processes slow down. At the slightest danger, the animal quickly wakes up. The bear's body temperature drops by only a few degrees - from 38 to 31-34. The state of sleep is preceded by the appearance of lethargy, slowing down of movement, and apathy in predators. This, on an instinctive level, makes you look for a place to build a lair.

During hibernation, the bear does not defecate or urinate: waste products are processed into proteins, which are so necessary for its existence. The body is completely rebuilt to a new mode. Sleep duration depends on natural conditions and accumulated nutrients and ranges from 2.5 months to six months. During this time, the animal loses about 50% of its mass.

It's no secret that the Siberian winter is a difficult test for many animals, and bears are no exception.

In common parlance, it is said that the bear hibernates, biologists say - in winter sleep. There are few details about this interesting process. main reason is the complexity of data collection.

Brown bear found throughout the reserve, both in all types of forests and in the mountain-tundra belt. On the territory of the reserve makes seasonal movements from forests to alpine belt and back, often using trails and country roads for roaming.

What does a bear eat before hibernation?

Before laying in a den, the owner of the taiga needs to accumulate nutrients. The bear is an omnivore, but most of its diet in the Kuznetsk Alatau, as in many other places, consists of food of plant origin: berries, herbaceous plants, acorns, nuts.

Pine cones are one of the bears' favorite treats and one of the best fattening foods. Young animals can climb trees after them and break off branches. But mostly they collect fallen cones from the ground. To get to the nuts, the bear collects the cones in a heap and crushes them with his paws, from where he then, lying on the ground, selects the nuts along with the shell with his tongue. The shell is partly thrown away during the meal, and partly eaten.

Often the attention of the bears is attracted by the stocks of nuts made by the chipmunks. Digging the holes of animals, the bears get to the nuts and eat them, often together with the owner. They do not miss the opportunity to feast on ant larvae, bird eggs or fish, they also hunt small rodents and hoofed animals. The brown bear rarely kills wild ungulates on his own, he mainly devours them in the form of carrion or selects the prey of other predators (wolf, lynx, wolverine).

The facts of eating by a predator of such species of wild ungulates as an elk, a deer, a roe deer are known. He fills up prey or found carrion with brushwood and keeps nearby until he finishes the carcass completely. If the animal is not very hungry, it often waits for several days until the meat becomes softer.

It is very important how fruitful the year was for fattening feed. Bad harvest years can greatly delay the timing of bears in dens, and the animals can continue to feed even in twenty-degree frosts and almost half a meter of snow, digging cones from under the snow, trying to gain the fat reserve necessary for wintering. In years favorable for food, adult bears accumulate a layer of subcutaneous fat up to 8-12 cm, and the weight of fat reserves reaches 40% of the total weight of the animal. It is this fat accumulated over the summer and autumn that the bear's body feeds on in winter, experiencing the harsh winter period with the least hardships.


Hungry years lead to rod bears

These are animals that have not had time to gain a sufficient supply of fat, which is why they cannot hibernate. Rods, as a rule, are doomed to death from hunger and frost or from a hunter. But not every bear that meets in the winter in the forest will be a connecting rod. During "after-hours" bears appear in the forest, whose sleep in the den is disturbed. Normally well-fed, but pulled out of hibernation, the bear is forced to look for a new, calmer haven for sleep. Often the sleep of animals is interrupted by human anxiety.

bear den

Before going to the den, the bear diligently confuses the tracks: it winds, goes along windbreaks and even goes backwards in its own footsteps. For lairs, deaf and reliable places are usually chosen. Often they are located along the edges of impenetrable swamps, along the shores of forest lakes and rivers, in windbreaks and logging sites. The brown bear arranges its winter dwelling in recesses under twisted roots or tree trunks, sometimes on a pile of brushwood or near an old woodpile. Less often, he chooses a cave for his house or digs deep earthen holes - ground lairs. The main condition is that the dwelling should be dry, quiet and isolated from the presence of unexpected guests. One of the signs of the proximity of the den is large bald spots in the moss, gnawed or broken trees. The beast insulates its shelter with branches, and layers of moss lines the litter. Sometimes the bedding layer reaches half a meter. It happens that several generations of bears use the same den.


At the beginning of winter, bears have offspring

From one to four, but more often two bear cubs are born. Babies are born blind, without hair and teeth. They weigh only half a kilogram and barely reach 25 cm in length. It is interesting that the nipples of the she-bear are not located along the line of the abdomen, as in most animals, but in the very warm places: in the armpits and inguinal cavities. The cubs feed on 20% fat milk from their still-sleeping mother and grow quickly. In a few months of such food, the cubs are completely transformed, and they leave the den already furry and nimble. True, still very dependent.


How does a bear sleep in a den

In the den, warm and safe, the bears sleep all the long and cold winter. Often the bear sleeps on its side, curled up in a ball, sometimes on its back, less often it sits with its head between its paws. If the animal is disturbed during sleep, it easily wakes up. Often the bear itself leaves the den during long thaws, returning to it at the slightest cold snap.

Animals falling into hibernation (for example, hedgehogs, chipmunks, etc.) become numb, their body temperature drops sharply, and, although vital activity continues, its signs are almost imperceptible. In a bear, the body temperature drops slightly, by only 3-5 degrees and fluctuates between 29 and 34 degrees. The heart beats rhythmically, although more slowly than usual, breathing becomes somewhat less frequent. The animal does not urinate or defecate. In any other animal in this case, in a week it would have come fatal poisoning, and the bears begin unique process of recycling waste products into useful proteins. A hard plug forms in the rectum, which some call a "sleeve". The predator loses it as soon as it leaves the lair. The cork consists of tightly pressed dry grass, the hair of the bear itself, ants, pieces of resin and needles.

Brown bears sleep alone, and only females who have cubs of the year go to bed with their cubs. The duration of hibernation depends on weather conditions, health and age of the animal. But usually this is the period from the second half of November to the first half of April.


Why does a bear suck its paw

There is a funny opinion that a bear sucks its paw during hibernation. But in fact, in January, February happens hard change skin on paw pads, while the old skin bursts, flakes, and itches a lot, and in order to somehow reduce these discomfort animal licks its paws.

It took more than one thousand years of natural selection to form such a complex system of adaptations, as a result of which bears acquired the ability to survive in areas with harsh climatic conditions. It remains only to be surprised at the diversity and wisdom of nature.

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